Microstructure‐property relation in alumina ceramics during post‐annealing process after laser shock processing

Laser shock processing ( LSP ) is a new surface engineering approach to introduce significant compressive residual stress into ceramics to improve their mechanical properties. However, LSP of ceramics may induce microcracks, which limit the further improvement of mechanical properties of ceramics. In this research, the effect of a post‐ LSP annealing process on α‐Al 2 O 3 ceramics was investigated. The annealing treatment can cause thermal relaxation of compressive residual stress generated by LSP while still maintain the positive attribute of LSP . The compressive residual stress was stabilized after annealing after 10 hours at 1100‐1300°C. The healing of microcracks in α‐Al 2 O 3 ceramics was observed during the post‐ LSP annealing process, which is caused by diffusion bonding mechanisms and accompanied by dislocation and void formation. The combination of the stabilized compressive residual stress and microcrack healing can improve the cracking resistance of α‐Al 2 O 3 ceramics to mechanical impact on the surface by 69%.